1. Field of the Invention
This invention relates broadly to processes for effecting mass transfer between fluids. More particularly, it relates to a method for promoting mass transfer in gas-absorption and liquid-extraction processes, as well as other processes involving preferential dissolution of a gas or liquid in a fluid solvent.
2. Related Art
Processes involving the preferential dissolution of a gas or liquid in a solvent are of great importance to industry. For example, gas-absorption and liquid-extraction processes are used extensively in the purification of raw materials and the separation of products from byproducts. Such processes commonly are conducted in columns for countercurrently contacting immiscible fluid phases. For instance, U.S. Pat. No. 3,762,133 (issued on Oct. 2, 1973, to Merriman, Pashley, Stephenson, and Dunthorn) describes a process in which a multicomponent feed gas is introduced continuously to the lower end of an absorber column in which the feed gas is contacted with a down-flowing stream of a liquid fluorocarbon for preferentially absorbing a gaseous component desired as the product. U.S. Pat. No. 3,785,120 (issued to the same inventors on Jan. 15, 1974) describes a process in which a multicomponent feed gas is similarly contacted to effect preferential absorption of various contaminants from the feed gas. To maintain a closed system, both of the patented processes typically operate with continuous gas recycle. That is, during further processing of the liquid solvent outflow from the absorber, a mixture of desorbed gases containing some solvent vapor is evolved; this mixture is recycled continuously to the feed being introduced to the absorber column.
U.S. Pat. No. 4,129,425, issued to Stephenson and Eby on Dec. 12, 1978, describes an improved gas-absorption process in which a feed gas is countercurrently contacted with a liquid fluorocarbon in a single "combination" column containing an absorption zone, an intermediate contacting zone, and a stripping zone.
Gas absorption, liquid extraction, and related processes are described generally in the following reference: Treybal, R. E. Mass Transfer Operations. New York: McGraw-Hill Book Co. (1968).
Although mass-transfer operations involving the use of a solvent to preferentially dissolve a component of a fluid mixture are relatively efficient, the development of a method for increasing dissolution efficiency by even a small amount would be of considerable value, especially if the method can be incorporated in already installed process systems.
3. Objects of the Invention
Accordingly, it is an object of this invention to provide a method for improving dissolution efficiency in mass-transfer processes involving the preferential dissolution of one fluid in another.
It is another object to provide a method for improving absorption efficiency in gas-absorption processes and extraction efficiency in liquid-extraction processes.
It is another object to provide a method for improving a process wherein a first fluid phase containing a given component is contacted with a second fluid phase for preferentially removing that component, the method being designed to enhance transfer of said component into the second phase.
It is another object to provide a relatively simple method for improving dissolution efficiency in proposed or existing systems for carrying out gas-absorption and liquid-extraction operations.
Other objects, advantages, and novel features will become evident from the description and figures.